The range of adjustment of a fuel adjustment valve provided on a carburetor main body may be limited to prevent an end user from increasing the supply of fuel delivered from the carburetor beyond a designed limit to comply with the regulations on the emission of small internal combustion engines. Some fuel adjustment valves include a needle member whose tip is configured to move into and out of a fuel passage provided in the carburetor main body so as to regulate the flow of fuel through the fuel passage.
To effect such a movement of the fuel adjust valve (needle member), a threaded hole is formed in the carburetor main body, and the fuel adjustment valve is threaded into this threaded hole so that the needle member may be advanced and backed out as desired by turning the fuel adjustment valve by using a suitable tool.